At the Metropolis First National Bank, the Shadow Thief is crawling down the building like a spider. Inside, Clark Kent and Jimmy Olsen are standing in line and Jimmy tells Clark he thinks once he wins the Pulitzer Prize all the girls will flock to him. Clark tells him that maybe he should be a rock star if he wants that kind of fame. Clark then notices a shadow moving toward the safe without a human connected to it. The bank manager notices that the shadow is heading toward the vault and he tells Angela to close the vault. Clark and Jimmy both run out of the bank through the rotating doors and into two separate phone booths that are next to each other. Jimmy calls Perry White to phone in the story and Clark changes into Superman. Superman runs back inside and tells the two bankers to stand aside, and just then, an explosion causes the vault door to blow off, and Superman catches it before it smashes Angela. Angela then directs Superman's attention to the floor, where the Shadow creature is crawling. Superman flies after it, but he passes right through the creature as if he was a ghost. The Shadow Thief tosses some gas grenades and the whole place is flooded with tear gas. Superman sucks all the gas up with his Super Breath, exits the bank and then flies up into the sky and releases the gas high over Metropolis.
At the Daily Planet Jimmy is venting his frustration on Perry because he ran a story with the headline: "Shadow Thief Succeeds: Superman Helpless!" Perry tells him he doesn't like to run stories like that, but it's news nonetheless. Lois and Clark then enter the room and Perry tells the three of them he wants to know who the Shadow Thief is, and he yells at them saying: "Get me that story!!" Jimmy then says: "Right chief." And Perry tells him "Don't call me chief!!" Outside of Perry's office, Clark, Lois and Jimmy decide they'll have to work together to find out who the Shadow Thief is. Lois agrees, but only if everyone tells her everything they find out.
At the residence of MacFarlane, Lex Luthor, reading a Daily Planet newspaper, tells MacFarlane that he's made front page news, and he's impressed with him, and he didn't think his suit would be such a theatrical display. Luthor is so impressed with MacFarlane's bank robbery that he will be giving him a raise, to which MacFarlane replies if the raise will be enough for new housing, or to get "me out of this dump". Lex tells him to recruit a gang, and meanwhile Lex will test the suit himself. He tells him that it's been years since he robbed his first candy store or held his first country hostage.
Later, at a jewelry store, Lex Luthor, disguised as the Shadow Thief tells the manager he wants the most expensive piece of jewelry he has, and he tells him to hurry because his car is double parked. But unknown to Lex, the manager pushes the police alarm to alert the police to the danger.
Meanwhile, at Police headquarters, Clark Kent is telling Inspector Henderson if he could just cross-check his files, he might be able to find a clue about the Shadow Thief, just then, they are alerted to the alarm from the jewelry store. As they are about to leave, the Inspector tells Clark that it looks like he'll be getting the story on the Shadow Thief after all. Clark pretends to be sick so he can sneak off and turn into Superman, and the Inspector leaves and tells him it's "your headline." When out of sight, he turns into Superman and flies off toward the jewelry store.
Back at the jewelrly store Lex tells the Jeweler that these jewels should be worth a fortune in France. Superman then enters the building. Superman tries to grab him, but the shadow suit gives him a ghost-like form, making it impossible for Superman to grab him. Lex tosses some grenades on the floor and then Superman, realizing they will explode in a matter of seconds, grabs them and flies outside into the sky. Lex runs outside, just as Inspector Henderson pulls up in his car. He enters the car and boots the Inspector out. Then he floors the gas pedal and takes off. Superman then arrives and speeds after the car. Lex sees Superman in his rear-view-mirror. He sharply turns right onto a street and bails out of the car and "shadows" his way down a manhole. Superman grabs the car and sets in a field. It almost crashed into what appeared to be a Daycare center.
Back at MacFarlane's place, Luthor returned and told him that it was marvelous. MacFarlane then tells Luthor he better get solid again, because if he stays a shadow for two hours, he'll remain like that forever. Luthor is angry that he hadn't told him that before, but he quickly regains his temper, and tells him that he now has the means to pull off the greatest robbery of all time and get rid of Superman forever.
Later, at Billiards Snooker, Lois and Jimmy are about to go inside, but Jimmy tells her he's not so sure that they should go in there, because even the cockroaches carry weapons in there. Inside, Lois puts a mini-microphone in her ear so that she can eavesdrop on other people's conversations. One Billiard gangster asks another what he's heard about the Shadow Thief starting a gang. The Gangster in shades tells him that anyone interested has to be at the Dockside Warehouse tonight. Lois tells Jimmy if they want to help Superman they've got to tell Clark. Jimmy tells her he'll go back to the Planet to get him and they'll meet her at the warehouse.
Back at the Daily Planet, Jimmy searches for Kent but can't find him, so he leaves a note on his desk that tells him where to meet him. But a fan sitting on the table adjacent to Clark's desk blows the note off his desk and into a trash can.
At the Dockside Warehouse, Lois watches as two men enter the warehouse, both are there for recruitment into the gang. Lois is worried because Clark and Jimmy are nowhere in sight, and it's getting late, and all the gangsters are already there, and Jimmy is trying to hail a cab, but unsuccessfully. So she decides she can't wait any longer and she enters with a flash light and sees the Shadow suits. She tries one of them on, and meanwhile, in the next room, MacFarlane asks the new recruits if they now understand how the suits work. Lois enters the room with her shadow suit. MacFarlane tells everyone to switch to shadow mode. Pressing buttons on their belts, they do just that, so Lois does likewise. The Shadow Thief then tells them that they're going to hit the Metropolis Mint.
Meanwhile, back at the Daily Planet, Perry and Clark are watching TV, where Luthor in his shadow suit is telling Metropolis that he is the leader of the shadow gang, that's made such a monkey out of Superman. Clark swears he knows that voice, but it's distorted by the shadow suit, so he can't tell it's Lex. But his super hearing knows it is familiar. Lex continues to say that he is going to rob the Metropolis Mint. Perry tells Clark to get over there fast.
At the mint, the police arrive, led by Inspector Henderson. He orders the other police officers to set up the defenses. The U.S. Army's National Guard are also on standby, waiting for the gang to strike. Luthor, leading the shadow gang, sneaks past the soldiers and approach a tank, and gas a Tank driver, which knocks him out. Shadow Thief asks Lex why they're hijacking the tank, when it's laser cannons would have no effect on Superman. Lex tells him that Kryptonite laser cannons will though. They then attach the Green K to the tank's circuit boards. Other Shadow gang members man the other tanks while MacFarlane, Luthor, Lois and two other members enter the building. As Superman arrives, the tanks, now powered by Green K, open fire on Superman, and Superman is injured. Superman wonders where they could have got the Green K. Dodging the blasts, he smashes all of the tanks...all but one that is. But he's too weak to attack the last tank. He is then blasted into a wall and it falls on top of him, burying him. He pulls himself from the rubble and then the shadow gang member fires another energy blast of Green K from the tank, but this time Superman dodges it, takes to flight and smashes the tank.
While inside the building, the other shadow gang members, led by Lex, locate the vault, Lois is still posing as a gang member. Superman then locates them with his X-Ray vision. Superman then gets to the vault room. But Lex had a chunk of Kryptonite and he throws it at him. Superman falls to the ground in agony. Lois runs up to the Kryptonite and tosses it out of the vault. Luthor then uses a laser gun to melt the ventilation shaft that they entered and traps her and Superman in the vault, and tosses the Green K back inside. Then, Shadow Thief sets off a device that's wired to blow up the whole vault in 30 seconds. They run out of the building. Back in the vault, Superman recognizes his voice now...it's Luthor. Superman then uses his heat vision to melt a whole that's just small enough for Lois to slip through in shadow form, and she gets the Green K away from him. Lois is afraid because she knows that if she stays in this form for much longer she'll be stuck like that forever, and she doesn't know how to solidify herself. Superman tells her to take him to the Shadow gang's hideout. And she tells him: "With pleasure."
They arrive at the warehouse, and Superman tells Lois to stay put, but she doesn't comply, which is definitely consistent with her character. Superman crashes through the window and tells Lex he wants Lois out of the suit...and he calls him by name. Luthor tells him he's flattered, but that he's actually a totally different criminal genius. Just then, one of the shadow gang members attacks Superman with a forklift. Superman tosses the forklift aside, smashing it into a wall. Superman realizes that he can't touch a shadow, but another shadow can, so he flies off and Lex tells the others that if he gets a shadow suit he'll be able to stop them. One of the Shadow gangsters shoots a bazooka at Superman but it has no effect on him, thanks to his invulnerability. He grabs the bazooka and bends it. Another gangster takes the shadow suits and tucks them under his own suit, so Superman can't get them. Superman gets an idea and he flies to Lois and lifts her up and flies off. Lex runs out of the warehouse and takes off his suit because he's worried when Superman gets ideas. He ditches the suit in a trash can and lights it on fire. He calls Miss Morganberry to bring the Limo to pick him up, and tells her a trip to Bermuda would be good.
Back in the Warehouse, the gang members are getting their money together when all of the sudden Superman lifts the entire building off the ground and tells them he'll throw them into the sun if they don't tell him how to get the suit off of Lois. He then throws them into the direction of the sun, and then flies up to them and asks them: "Well?" And so they agree and give her the code. He makes them throw out their shadow suits, and he then saves them from flying into the sun.
Later, Back on the ground, Lois is out of the suit, and Superman tells her she's a lovely as ever. She asks him if he would have really thrown them into the sun. And he tells her of course not. Inspector Henderson and the rest of the police arrive just then and he tells them the evidence is inside the building. But there was unfortunately not enough evidence to connect Luthor to the crime. But the Inspector tells him one of these days they'll have enough evidence to throw him behind bars.
- This is the last appearance of Lex Luthor. He made his first appearance in The New Adventures of Superman episode Merlin's Magic Marbles, which interestingly enough involved a shadow potion instead of a shadow suit.
- Inspector Henderson made his first and only appearance in this episode.
- The episode title refers to the LexCorp employees that wear shadow suits.
- The title is a reference to the film Night of the Living Dead, which was a film about flesh-eating Zombies.